how to know the current Zoom level in D3.js

Question

I have a problem since a few days. I have a graph and when I use Zoom Behavior it works, but I need to know when I reach maximum zoom to load new given

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Answer 1

In the draw function the current event will have the zoom level (d3.event.scale as you mentioned). Also if you keep the behaviour around like:

var zm = d3.behavior.zoom().x(x).scaleExtent([1,10]).on("zoom", draw);

Then you can find the current zoom level by calling:

zm.scale();